We estimate the performance of ultrawideband (UWB) signal transmissions for a multi-cell environment combined with a large virtual cell using radioover-fiber (ROF) technologies. For a large virtual cell, UWB signal transmissions have been evaluated in the overlapped area between cells using a realistic channel model based on a modified Δ-k model. The effects of multipath interference and delay time at the overlapped area have been evaluated in terms of link margins and bit error rates using Rake receivers. Our simulation results suggest that the delay time of about 125ps significantly affects the link margin for PPM. The optimum peak-to-peak voltage (V p-p) of Mach-Zehnder modulators (MZM) has been obtained to be 2.4V for the best link margin. Considering link margins, bite error rates (BER), and packet error rates (PER), the BPM modulation format has better performance than the PPM modulation format.